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How to schedule feature releases

Placeholders

Placeholders in the code samples below are delimited by angle brackets (i.e. <placeholder-name>). You will need to replace them with the values that are correct in your situation for the code samples to run properly.

There's a whole host of reasons why you may want to schedule the release of a feature, such as:

  • to release a feature at a specific date and time (for a product launch, for instance)
  • to make a feature available only up until a specific moment (for a contest cutoff, for instance)
  • to make a feature available during a limited period (for a 24 hour flash sale, for instance)

There are two distinct ways to do this, depending on which version of Unleash you are running:

In this guide we'll schedule a feature for release at some point in time. The exact same logic applies if you want to make a feature available until some point in the future. Finally, if you want to only make a feature available during a limited time period, you can easily combine the two options.

Prerequisites​

This guide assumes that you've got the following:

  • some basic experience with Unleash
  • a running instance of Unleash and connected clients (where applicable)
  • an existing feature flag that you want to schedule the release for

Schedule feature releases with strategy constraints​

Strategy constraints are the easiest way to schedule feature releases (as long as your SDKs are up to date). You can use this approach with any strategy you want. The strategies will work just as they normally do, they just won't become active until the specified time. For example: with the standard strategy, the feature would become available to all your users at the specified time; with a gradual rollout, the rollout would start at the specified time.

Step 1: Add an activation strategy with a date-based constraint​

Scheduling a release via the UI​

To schedule a feature release via the UI:

  1. Add the desired activation strategy to the feature
  2. Open the constraint creator by using the "Add constraint" button
  3. Add a date-based constraint by selecting the currentTime context field (step 1 in the below image), choosing the DATE_AFTER operator (step 2), and setting the point in time where you want the feature to be available from (step 3) A strategy constraint specifying that the activation strategy should be enabled at 12:00 AM, November 25th 2022. There are visual call-outs pointing to the relevant settings mentioned above.

Scheduling a release via the API​

To add an activation strategy via the Admin API, use the feature's strategies endpoint to add a new strategy (see the API documentation for adding strategies to feature flags for more details).

The payload's "name" property should contain the name of the strategy to apply (see activation strategies reference documentation for all built-in strategies' modeling names).

The "constraint" object should have the same format as described in the code sample below. The activation date must be in an RFC 3339-compatible format, e.g. "1990-12-31T23:59:60Z".

Add a feature activation strategy with a scheduled activation time.
POST <unleash-url>/api/admin/projects/<project-id>/features/environments/<environment>/strategies
Authorization: <API-token>
content-type: application/json

{
  "name": "default",
  "constraints": [
    {
      "value": "<activation-date>",
      "operator": "DATE_AFTER",
      "contextName": "currentTime"
    }
  ]
}

The "operator" property in the code sample can be replaced with any of the other date and time-based operators according to your needs.

Schedule feature releases with custom activation strategies​

To schedule feature releases without using strategy constraints, you can use custom activation strategies. This requires defining a custom strategy and then implementing that strategy in your SDKs. For detailed instructions on how to do either of these things, refer to their respective how-to guides:

Step 1: Define and apply a custom activation strategy​

Define a strategy that takes a parameter that tells it when to activate (visit the custom activation strategy reference documentation for full details on definitions):

  1. Give the strategy a name. We'll use enableAfter.
  2. Give the strategy a required string parameter where the user can enter the time at which the feature should activate. Be sure to describe the format that the user must adhere to.
  3. Save the strategy

Apply the strategy to the feature flag you want to schedule.

A custom activation strategy definition for a strategy called `enableAfter`. It takes a required parameter called `start time`: a string in a date format.

Step 2: Implement the custom activation strategy in your clients​

In each of the client SDKs that will interact with your feature, implement the strategy (the implementation how-to guide has steps for all SDK types).